Catalyst comprising a zeolite Y globally non-dealuminated and containing boron and/or silicon

ABSTRACT

The present invention relates to a hydrocracking process including contacting a hydrocarbon feed with a catalyst which is carried out at a pressure of at least 2 MPa, a temperature of at least 230° C., using a quantity of hydrogen of at least 100 Nl hydrogen/l of feed and with an hourly space velocity of 0.1-10 h −1 . The catalyst includes 
     0.1-99.7% by weight of at least one alumina matrix; 
     0.1-80% by weight of at least one globally non dealuminated Y zeolite with a lattice parameter of more than 2.438 nm, a global SiO 2 /Al 2 O 3  mole ratio of less than 8, and a framework SiO 2 /Al 2 O 3  mole ratio of less than 21 and more than the global SiO 2 /Al 2 O 3  mole ratio; 
     0.1-30% by weight of at least one group VIII metal and/or 1-40% by weight of at least one group VIB metal (% oxide); 
     0.1-20% by weight of at least one promoter element selected from the group formed by boron and silicon (% oxide); 
     0-20% by weight of at least one group VIIA element; 
     0-20% by weight of phosphorous (% oxide); and 
     0.1-20% by weight of at least one group VIIB element.

This application is a divisional of U.S. Ser. No. 09/305,296, filed onMay 5, 1999, now U.S. Pat. No. 6,420,296.

The present invention relates to a catalyst for hydrocrackinghydrocarbon-containing feeds, said catalyst comprising at least onemetal selected from group VIB and group VIII (group 6 and groups 8, 9and 10 in the new notation for the periodic table: Handbook of Chemistryand Physics, 76^(th) edition, 1995-96), preferably molybdenum ortungsten, cobalt, nickel or iron, associated with a support comprisingan amorphous or low crystallinity oxide type alumina and a nondealuminated Y zeolite with a lattice parameter of more than 2.438 nm.The alumina matrix of the catalyst comprises boron and/or silicon andoptionally phosphorous, and optionally at least one element from groupVIIA (group 17, the halogens), in particular fluorine, and optionally atleast one group VIIB element.

The present invention also relates to processes for preparing saidcatalyst, and to its use for hydrocracking hydrocarbon-containing feedssuch as petroleum cuts, or cuts from coal containing sulphur andnitrogen in the form of organic compounds, such feeds possiblycontaining metals and/or oxygen.

Conventional hydrocracking of petroleum feeds is a very importantrefining process which produces lighter fractions such as gasoline, jetfuel and light gas oil from surplus heavy feeds, which lighter fractionsare needed by the refiner so that he can match production to demand. Theimportance of catalytic hydrocracking over catalytic cracking is that itcan provide very good quality middle distillates, jet fuels and gasoils.

All catalysts used for hydrocracking are bifunctional, combining an acidfunction and a hydrogenating function. The acid function is supplied bylarge surface area supports (150 to 800 m²/g in general) with asuperficial acidity, such as halogenated aluminas (in particularfluorinated or chlorinated), combinations of boron and aluminium oxides,amorphous silica-aluminas and zeolites. The hydrogenating function issupplied either by one or more metals from group VIII of the periodictable, such as iron, cobalt, nickel, ruthenium, rhodium, palladium,osmium, iridium or platinum, or by a combination of at least one metalfrom group VIB of the periodic table such as chromium, molybdenum ortungsten, and at least one group VIII metal, preferably non noble.

The equilibrium between the two, acid and hydrogenating, functions isthe fundamental parameter which governs the activity and selectivity ofthe catalyst. A weak acid function and a strong hydrogenating functionproduces low activity catalysts which generally operate at a hightemperature (390° C. or above), and at a low supply space velocity (HSV,expressed as the volume of feed to be treated per unit volume ofcatalyst per hour, and is generally 2 or less), but have very goodselectivity for middle distillates. In contrast a strong acid functionand a weak hydrogenating function produces very active catalysts butselectivities for middle distillates are poor. Further, a weak acidfunction is less sensitive to deactivation, in particular bynitrogen-containing compounds, than a strong acid function. The problemis thus the proper selection of each of the functions to adjust theactivity/selectivity balance of the catalyst.

Weakly acid supports are generally constituted by amorphous or lowcrystallinity oxides. Weakly acidic supports include amorphoussilica-aluminas. Certain catalysts on the hydrocracking market areconstituted by silica-alumina combined with a combination of sulphidesof groups VIB and VIII metals. Such catalysts enable feeds containinglarge quantities of heteroatomic poisons, sulphur and nitrogen, to betreated. The selectivity of such catalysts for middle distillates isvery good. The disadvantage of such catalytic systems based on anamorphous support is their low activity.

Supports with a high acidity generally contain a dealuminated zeolite,for example a dealuminated Y type zeolite or USY (Ultra Stable Yzeolite), combined with a binder, for example alumina. Certain catalystson the hydrocracking market are constituted by a dealuminated Y zeoliteand an alumina combined either with a group VIII metal or with acombination of sulphides of group VIB and VIII metals. Such catalystsare preferably used to treat feeds containing less than 0.01% by weightof heteroatomic poisons, sulphur and nitrogen. Such systems are veryactive and the products formed are of high quality. The disadvantage ofsuch catalytic systems based on a zeolitic support is that theirselectivity for middle distillates is a little poorer than catalystsbased on an amorphous support, and a high sensitivity to nitrogencontent. Such catalysts can only tolerate low amounts of nitrogen in thefeed, in general less than 100 ppm by weight.

The Applicant has discovered that to obtain a hydrocracking catalystwith good activity and good stability for feeds with high nitrogencontents, it is advantageous to combine an alumina type acidic amorphousoxide matrix doped with at least one element selected from boron andsilicon, and optionally phosphorous and optionally at least one groupVIIA element, in particular fluorine, with a highly acidic globallydealuminated Y zeolite.

The term “globally non dealuminated zeolite” means a Y zeolite with afaujasite structure (“Zeolite Molecular Sieves: Structure, Chemistry andUses”, D. W. BRECK, J. Wiley & Sons, 1973). The lattice parameter ofthis zeolite may have been reduced by extracting aluminium from thestructure or framework during its preparation but the globalSiO_(2/)Al₂O₃ ratio is not changed since the aluminium atoms have notbeen chemically extracted. The zeolite crystals thus contain aluminiumextracted from the framework in the form of extra-framework aluminium.Such a globally non dealuminated zeolite thus has a silicon andaluminium composition, expressed as the global SiO₂/Al₂O₃ ratio,equivalent to the non dealuminated starting Y zeolite. This globally nondealuminated Y zeolite can be in its hydrogen form, i.e., at leastpartially exchanged with metal cations, for example using cations ofalkaline-earth metals and/or cations of rare earth metals with atomicnumber 57 to 71 inclusive.

The catalyst of the present invention generally comprises at least onemetal selected from the following groups in the following amounts, as apercentage by weight with respect to the total catalyst mass:

0.1% to 30% of at least one group VIII metal and/or 1-40% of at leastone group VIB metal (% oxide);

1% to 99.7%, preferably 10% to 98%, more preferably 15% to 95%, of atleast one amorphous or low crystallinity alumina matrix;

0.1% to 80%, or 0.1% to 60%, preferably 0.1% to 50%, of at least oneglobally non dealuminated Y zeolite with a lattice parameter of morethan 2.438 nm, a global SiO₂/Al₂O₃ mole ratio of less than 8, and aframework SiO₂/Al₂O₃ mole ratio, calculated using theFichtner-Schmittler correlation (Cryst. Res. Tech. 1984, 19, K1) of lessthan 21 and above the global SiO₂/Al₂O₃ ratio;

0.1% to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10%, of atleast one promoter element selected from the group formed by boron andsilicon (% oxide);

and optionally:

0 to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10%, ofphosphorous (% oxide);

0 to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10% by weight,of at least one element selected from group VIIA, preferably fluorine;

0 to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10% by weight,of at least one element selected from group VIIB, preferably manganeseor rhenium.

The catalysts obtained in the present invention are formed into grainsof different shapes and dimensions. They are generally used in the formof cylindrical or polylobed extrudates such as bilobes, trilobes, orpolylobes with a straight or twisted shape, but they can also beproduced and used in the form of compressed powder, tablets, rings,beads or wheels. The specific surface area is measured by nitrogenadsorption using the BET method (Brunauer, Emmett, Teller, J. Am. Chem.Soc., vol. 60, 309-316 (1938)) and is more than 140 m²/g, the porevolume measured using a mercury porisimeter is in the range 0.2 to 1.5cm³/g and the pore size distribution may be unimodal, bimodal orpolymodal. Preferably, the distribution of the catalysts of the presentinvention is unimodal.

The activity of said catalyst for hydrocracking vacuum gas oil type cutsis higher than that of known catalytic formulae of the prior art.Without wishing to be bound by any particular theory, it appears thatthe particularly high activity of the catalysts of the present inventionis due to a reinforcement in the acidity of the catalyst by the presenceof an alumina matrix acidified by the addition of boron and/or silicon,which also improves the hydrodenitrogenation properties of the activephase comprising at least one group VIB metal and optionally at leastone group VIII metal, and by the presence of the highly acidic Y zeolitea large portion of the acidity of which will be neutralised bynitrogen-containing compounds, but the acidic sites which remain underthe operating conditions will result in sufficient hydrocrackingactivity for the catalyst.

The catalyst of the present invention can be prepared using any of themethods which are known to the skilled person.

Advantageously, it is obtained by mixing a source of alumina, optionallydoped with boron and/or silicon, and a source of the starting Y zeolite,the mixture then being formed. All or a portion of the group VIII and/orVIB elements, the group VIIA element and the phosphorous is introducedduring mixing, or all of it can be introduced after forming (preferred).Forming is followed by calcining at a temperature of 250° C. to 600° C.One preferred forming method consists of mixing the starting Y zeolitein a moist alumina gel for a few tens of minutes, then passing the pasteobtained through a die to form extrudates with a diameter which ispreferably in the range 0.4 to 4 mm.

The alumina source is normally selected from the group formed by aluminagels and alumina powders obtained by calcining aluminium hydroxides andoxyhydroxides. Preferably, matrices containing alumina are used, in anyof the forms known to the skilled person, for example gamma alumina.

The preferred Y zeolite source is a Y zeolite powder characterized bydifferent specifications: a lattice parameter of more than 2.451 nm; aglobal SiO₂/Al₂O₃ mole ratio of less than 8, a framework SiO₂/Al₂O₃ moleratio, calculated using the Fichtner-Schmittler correlation (Cryst. Res.Tech. 1984, 19, K1) of less than 11; a sodium content of less than 0.2%by weight determined for the zeolite calcined at 1100° C.; and aspecific surface area, determined using the BET method, of more thanabout 400 m²/g, preferably more than 600 m²/g.

The catalyst also comprises a hydrogenating function. The hydrogenatingfunction is provided by at least one metal or compound of a metal fromgroup VIB such as molybdenum or tungsten. A combination of at least onemetal or compound of a metal from group VIB of the periodic table (inparticular molybdenum or tungsten) and at least one metal or compound ofa metal from group VIII of the periodic table, preferably non noble (inparticular cobalt or nickel) can be used.

The hydrogenating function as defined above can be introduced into thecatalyst at various stages of the preparation and in various manners. Itcan be introduced only partially (in the case, for example ofcombinations of oxides of groups VIB and VIII metals) or completely onmixing the alumina source, the remaining hydrogenating element(s) thenbeing introduced after mixing, more generally after calcining.Preferably, the group VIII metal is introduced simultaneously with orafter the group VIB metal, regardless of its mode of introduction. Itcan be introduced by one or more ion exchange operations carried out onthe calcined support constituted by the zeolite dispersed in the aluminamatrix, using solutions containing precursor salts of the selectedmetals when these are from group VIII. It can be introduced by one ormore steps for impregnating the formed and calcined support using asolution of precursors of group VIII metal oxides (in particular cobaltor nickel) when the precursors of the group VIB metal oxides (inparticular molybdenum or tungsten) have already been introduced onmixing the support. Finally, it can also be introduced by one or moresteps for impregnating the calcined support constituted by the zeoliteand alumina matrix, optionally doped with B, Si, P and/or F, usingsolutions containing precursors of oxides of group VIB and/or group VIIImetals, the precursors of the oxides of the group VIII metal preferablybeing introduced after those of group VIB or at the same time as thelatter.

When the elements are introduced in a plurality of steps forimpregnating the corresponding precursor salts, an intermediatecalcining step must be carried out on the catalyst at a temperature inthe range 250° C. to 600° C.

The sources of the group VIB element which can be used are well known tothe skilled person. As an example, preferred sources of molybdenum andof tungsten are ammonium salts and oxides such as ammonium molybdate,ammonium heptamolybdate and ammonium tungstate.

The sources of the group VIII element which can be used are well knownto the skilled person. As an example, nitrates, sulphates and halidescan be used.

The sources of the group VIIB elements which can be used are well knownto the skilled person. Preferably, ammonium salts, nitrates andchlorides are used.

The phosphorous can be introduced into the catalyst at various stages inthe preparation and in a variety of manners. One preferred methodconsists of preparing an aqueous solution of at least one group VIBelement and optionally at least one group VIII element and a phosphorouscompound and carrying out dry impregnation, in which the pore volume ofthe precursor is filled with the solution containing the group VIBmetal, the optional group VIII metal, phosphorous and the optional groupVIIA element.

Molybdenum and/or tungsten impregnation can be facilitated by addingphosphoric acid to the solutions, which enables phosphorous to beintroduced as well to promote the catalytic activity. Other phosphorouscompounds can be used, as is well known to the skilled person.

The phosphorous and the element selected from group VIIA halide ions canbe introduced by one or more impregnation operations using an excess ofsolution, carried out on the calcined precursor.

The preferred phosphorous source is orthophosphoric acid H₃PO₄, but itssalts and esters such as ammonium phosphates are also suitable.Phosphomolybdic acid and its salts, phosphotungstic acid and its saltscan advantageously be used. Phosphorous can, for example, be introducedin the form of a mixture of phosphoric acid and a basic organic compoundcontaining nitrogen, such as ammonia, primary and secondary amines,cyclic amines, pyridine group compounds, quinolines, and pyrrole groupcompounds.

Introducing boron requires an aqueous solution containing boron (B) tobe deposited. One preferred method consists of preparing an aqueoussolution of at least one boron salt such as ammonium biborate orammonium pentaborate in an alkaline medium and in the presence of waterand carrying out “dry” impregnation, in which the pore volume of theprecursor is filled with the solution containing the B. This method fordepositing B is better than the conventional method employing analcoholic solution of boric acid.

The B and the optional element selected from group VIIA, the halogens,preferably fluorine (F), can be introduced into the catalyst at variousstages of the preparation and in various manners.

The phosphorous (P), B and the element selected from halide ions ofgroup VIIA can be separately introduced into the calcined precursorusing one or more impregnation operations with an excess of solution.

Thus, for example, in the preferred case where, for example, theprecursor is a catalyst of the nickel-molybdenum-phosphorous supportedon alumina-Y zeolite type, it is possible to impregnate this precursorwith an aqueous solution of biborate, to dry, for example at 80° C.,then to impregnate with a solution of ammonium fluoride, to dry. forexample at 80° C., and to calcine, for example and preferably in air ina traversed bed, for example at 500° C. for 4 hours.

Introducing silicon requires an aqueous solution containing silicon tobe deposited. One preferred method of the invention consists ofpreparing an aqueous solution containing a silicone type silicon (Si)compound in the form of an emulsion and to carry out “dry” impregnation,in which the pore volume of the precursor is filled with the solutioncontaining the Si. This method for depositing Si is better than theconventional method employing an alcoholic solution of ethylorthosilicate in alcohol.

A variety of silicon sources can be used. Examples are ethylorthosilicate Si(OEt)₄, silicones, siloxanes, polysiloxanes, andhalogenated silicates such as ammonium fluorosilicate (NH₄)₂SiF₆ orsodium fluorosilicate Na₂SiF₆. Silicomolybdic acid and its salts, andsilicotungstic acid and its salts can also advantageously be used.Silicon can be added, for example, by impregnating ethyl silicate insolution in a water/alcohol mixture. Silicon can be added, for example,by impregnation using an emulsion of a silicone in water.

Sources of group VIIA elements which can be used are well known to theskilled person. As an example, fluoride anions can be introduced in theform of hydrofluoric acid or its salts. Such salts are formed withalkali metals, ammonium or an organic compound. In the latter case, thesalt is advantageously formed in the reaction mixture by reacting theorganic compound with hydrofluoric acid. It is also possible to usehydrolysable compounds which can liberate fluoride anions in water, suchas ammonium fluorosilicate (NH₄)₂SiF₆, silicon tetrafluoride SiF₄ orsodium fluorosilicate Na₂Sif₆. Fluorine can be introduced, for example,by impregnating an aqueous hydrofluoride or ammonium fluoride solution.

The catalysts obtained are used for hydrocracking, in particular ofvacuum distillate, deasphalted residues or hydrotreated type heavyhydrocarbon-containing feeds. The heavy feeds are preferably constitutedby at least 80% by volume of compounds with boiling points of at least350° C., preferably in the range 350° C. to 580° C. They generallycontain heteroatoms such as sulphur and nitrogen. The nitrogen contentis usually in the range 1 to 5000 ppm by weight and the sulphur contentis in the range 0.01% to 5% by weight.

The hydrocracking conditions such as temperature, pressure, hydrogenrecycle ratio, and hourly space velocity, can vary widely depending onthe nature of the feed, the quality of the desired products and thefacilities available to the refiner. The temperature is generally morethan 200° C. and usually in the range 250° C. to 480° C. The pressure ismore than 0.1 MPa and usually more than 1 MPa. The hydrogen recycleratio is a minimum of 50 and usually in the range 80 to 5000 normalliters of hydrogen per liter of feed. The hourly space velocity isgenerally in the range 0.1 to 20 volumes of feed per volume of catalystper hour.

The catalysts of the present invention preferably undergo sulphurisationto transform at least part of the metallic species to the sulphidebefore bringing them into contact with the feed to be treated. Thisactivation treatment by sulphurisation is well known to the skilledperson and can be carried out using any method already described in theliterature.

One conventional sulphurisation method which is well known to theskilled person consists of heating in the presence of hydrogen sulphideto a temperature in the range 150° C. to 800° C., preferably in therange 250° C. to 600° C., generally in a traversed bed reaction zone.

Finally, the composition of the catalyst renders it easy to regenerate.

The catalyst can be used under variable hydrocracking conditions withpressures of at least 2 MPa, a reaction temperature of at least 230° C.,an H₂/feed ratio of at least 100 N1 H₂/l of feed and an hourly spacevelocity of 0.1-10 h⁻¹.

The initial boiling point of the hydrocarbon-containing feeds treated isat least 150° C., preferably at least 350° C. more advantageously a cutboiling between 350-580° C.

The catalyst of the present invention can be used for hydrocracking avariety of hydrocarbon-containing cuts, for example vacuum distillatetype cuts containing large amounts of sulphur and nitrogen. In a firstpartial hydrocracking implementation, the degree of conversion is below55%. The catalyst of the invention is thus used at a temperature whichis generally 230° C. or more, or 300° C., generally at most 480° C., andusually in the range 350° C. to 450° C. The pressure is generally morethan 2 MPa and 12 MPa or less. A moderate pressure range is ofparticular interest, namely 7.5-11 MPa, preferably 7.5-10 MPa or 8-11MPa, advantageously 8.5-10 MPa. The quantity of hydrogen is a minimum of100 normal liters of hydrogen per liter of feed and usually in the range200 to 3000 normal liters of hydrogen per liter of feed. The hourlyspace velocity is generally in the range 0.1 to 10 h⁻¹. Under theseconditions, the catalysts of the present invention have betteractivities for conversion, hydrodesulphuration and hydrodenitrogenationthan commercially available catalysts.

In this implementation, the catalyst of the present invention can beused for partial hydrocracking, advantageously under moderate hydrogenpressure conditions, of cuts such as vacuum distillates containing highsulphur and nitrogen contents which have already been hydrotreated. Inthis hydrocracking mode, the degree of conversion is below 55%. In thiscase, the petroleum cut is converted in two steps, the catalysts of theinvention being used in the second step. The catalyst used in the firststep has a hydrotreatment function and comprises a matrix, preferablyalumina-based, preferably containing no zeolite, and at least one metalwith a hydrogenating function. Said matrix can also be constituted by,or comprise, silica, silica-alumina, boron oxide, magnesia, zirconia,titanium oxide or a combination of these oxides. The hydrotreatmentfunction is ensured by at least one metal or compound of a metal fromgroup VIII, such as nickel or cobalt. A combination of at least onemetal or compound of a metal from group VIB (in particular molybdenum ortungsten) and at least one metal or compound of a metal from group VIII(in particular cobalt or nickel) can be used. The total concentration ofgroups VIB and VIII metal oxides is preferably in the range 5% to 40% byweight, preferably in the range 7% to 30% by weight, and the weightratio, expressed as the metal oxide of the group VIB metal (or metals)to that of the group VIII metal (or metals), is in the range 1.25 to 20,preferably in the range 2 to 10. Further, this catalyst can containphosphorous. The phosphorous content, expressed as the concentration ofphosphorous pentoxide P₂O₅, is generally at most 15%, preferably in therange 0.1% to 15% by weight, and more preferably in the range 0.15% to10% by weight. It can also contain boron in a ratio B/P=1.05-2 (atomic),the sum of the B and P contents, expressed as the oxides, being in therange 5% to 15% by weight.

The first step is generally carried out at a temperature of 350-460° C.,preferably 360-450° C.; at a total pressure of 2 to 12 MPa, preferably7.5-11 MPa, 7.5-10 MPa or 8-11 MPa or 8.5-10 MPa; and the hourly spacevelocity is 0.1-5 h⁻¹, preferably 0.2-2 h⁻¹, with a quantity of hydrogenat least 100 Nl/Nl of feed, preferably 260-3000 Nl/Nl of feed.

In the conversion step using the catalyst of the invention (or secondstep), the temperatures are generally 230° C. or more and usually in therange 300° C. to 430° C. The pressure is generally in the range 2 to 12MPa, preferably 7.5-11 MPa or 7.5-10 MPa or 8-11 MPa or 8.5-10 MPa. Thequantity of hydrogen is a minimum of 100 l/l of feed and usually in therange 200 to 3000 liters of hydrogen per liter of feed. The hourly spacevelocity is generally in the range 0.15 to 10 h⁻¹.

Under these conditions, the activities of the catalysts of the presentinvention are better for conversion, hydrodesulphuration, andhydrodenitrogenation and the selectivity for middle distillates isbetter than that of commercially available catalysts. The service lifeof the catalysts is also improved in the moderate pressure range.

In a second implementation, the catalyst of the present invention can beused for hydrocracking under high hydrogen pressure conditions of atleast 8.5 MPa, preferably at least 9 MPa or at least 10 MPa. The treatedcuts are, for example, vacuum distillates containing high sulphur andnitrogen contents which have already been hydrotreated. In thishydrocracking mode, the degree of conversion is more than 55%. In thiscase, the petroleum cut conversion process is carried out in two steps,the catalyst of the invention being used in the second step.

The catalyst for the first step has a hydrotreatment function andcomprises a matrix, preferably alumina-based, preferably containing nozeolite, and at least one metal with a hydrogenating function. Saidmatrix can also be constituted by, or comprise, a silica,silica-alumina, boron oxide, magnesia, zirconia, titanium oxide or acombination of these oxides. The hydro-dehydrogenating function isensured by at least one group VIII metal or compound of a metal such asnickel or cobalt. A combination of at least one metal or compound of ametal from group VIB (in particular molybdenum or tungsten) and at leastone metal or compound of a metal from group VIII (in particular cobaltor nickel) can be used. The total concentration of group VIB and VIIImetal oxides is in the range 5% to 40% by weight, preferably in therange 7% to 30% by weight, and the weight ratio, expressed as the metaloxide of the group VIB metal (or metals) to that of the group VIII metal(or metals) is preferably in the range 1.25 to 20, more preferably inthe range 2 to 10. Further, this catalyst can contain phosphorous. Thephosphorous content, expressed as the concentration of phosphorouspentoxide P₂O₅, is at most 15%, preferably in the range 0.1% to 15% byweight, and more preferably in the range 0.15% to 10% by weight. It canalso contain boron in a ratio B/P=1.02-2 (atomic), the sum of the B andP contents, expressed as the oxides, preferably being in the range 5% to15% by weight.

The first step is generally carried out at a temperature of 350-460° C.,preferably 360-450° C.; the pressure is more than 8.5 MPa, preferablymore than 10 MPa; the hourly space velocity is 0.1-5 h⁻¹, preferably0.2-2 h⁻¹; and the quantity of hydrogen is at least 100 Nl/Nl of feed,preferably 260-3000 Nl/Nl of feed.

For the conversion step using the catalyst of the invention (or secondstep), the temperatures are generally 230° C. or more, usually in therange 300° C. to 430° C. The pressure is generally more than 8.5 MPa,preferably more than 10 MPa. The quantity of hydrogen is a minimum of100 l/l of feed, usually in the range 200 to 3000 liters of hydrogen perliter of feed. The hourly space velocity is generally in the range 0.15to 10 h⁻¹.

Under these conditions, the activities of the catalysts of the presentinvention are better for conversion and the selectivity for middledistillates is better than that for commercially available catalysts,even though the zeolite contents are considerably lower than those ofcommercially available catalysts.

The following examples illustrate the present invention without in anyway limiting its scope.

EXAMPLE 1 Preparation of a Support Containing a Non Dealuminated YZeolite

Large quantities of a hydrocracking catalyst support containing aglobally non dealuminated Y zeolite were produced so as to enabledifferent catalysts based on the same support to be prepared. To thisend, 19.7% by weight of a non dealuminated Y zeolite with a latticeparameter of 2.453 nm, a global SiO₂/Al₂O₃ ratio of 6.6 and a frameworkSiO₂/Al₂O₃ ratio of 8.6 was used, which was mixed with 80.3% by weightof a matrix composed of ultrafine tabular boehmite or alumina gel soldby Condéa Chemie GmbH under the trade name SB3. This powder mixture wasthen mixed with an aqueous solution containing 66% nitric acid (7% byweight of acid per gram of dry gel) then mixed for 15 minutes. Aftermixing, the paste obtained was passed through a die with cylindricalorifices with a diameter of 1.4 mm. The extrudates were dried overnightat 120° C. then calcined at 550° C. for 2 hours in moist air containing7.5% by volume of water. Cylindrical extrudates 1.2 mm in diameter wereobtained with a specific surface area of 351 m²/g, a pore volume of 0.58cm³/g and a unimodal pore size distribution centred on 10 nm. An X raydiffraction analysis of the matrix revealed that it was composed of lowcrystallinity cubic gamma alumina and Y zeolite with a lattice parameterof 2.444 nm, a global SiO₂/Al₂O₃ ratio of 6.7 with a frameworkSiO₂/Al₂O₃ ratio of 13.9.

EXAMPLE 2 Preparation of Hydrocracking Catalysts Containing a NonDealuminated Y Zeolite

Extrudates of the support containing a non dealuminated Y zeolite with alattice parameter of 2.444 nm, a global SiO₂/Al₂O₃ ratio of 6.7 and aframework SiO₂/Al₂O₃ ratio of 13.9 prepared in Example 1 were dryimpregnated with an aqueous solution of a mixture of ammoniumheptamolybdate and nickel nitrate, dried overnight at 120° C. in air andfinally calcined at 550° C. in air. The oxide weight contents ofcatalyst CZ3 obtained are shown in Table 1. The final CZ3 catalystcontained 16.6% by weight of Y zeolite. X ray diffraction analysis ofthe matrix revealed that it was composed of low crystallinity cubicgamma alumina and Y zeolite with a lattice parameter of 2.444 nm, aglobal SiO₂/Al₂O₃ ratio of 6.6 and a framework SiO₂/Al₂O₃ ratio of 14.2.

Catalyst CZ3 was then impregnated with an aqueous solution comprisingammonium biborate. After ageing at room temperature in an atmospheresaturated with water, the impregnated extrudates were dried overnight at120° C. then calcined at 550° C. for 2 hours in dry air. Catalyst CZ3Bwas obtained: NiMo/alumina-Y doped with boron. In the same way, catalystCZ3Si was prepared by impregnating catalyst CZ3 with a Rhodorsil EP1(Rhone-Poulenc) silicone emulsion. The impregnated extrudates were driedovernight at 120° C. then calcined at 550° C. for 2 hours in dry air.Finally, catalyst CZ3BSi was prepared by impregnating catalyst CZ3 withan aqueous solution comprising ammonium biborate and Rhodorsil EP1(Rhone-Poulenc) silicone emulsion. The impregnated extrudates were driedovernight at 120° C. then calcined at 550° C. for 2 hours in dry air.

Extrudates of the support containing the Y zeolite of Example 1 werealso dry impregnated with an aqueous solution of a mixture of ammoniumheptamolybdate, nickel nitrate and orthophosphoric acid, dried overnightat 120° C. in air and finally calcined at 550° C. in air. The oxideweight contents of catalyst CZ3P obtained are shown in Table 1. Thefinal CZ3P catalyst contained 15.7% by weight of Y zeolite. X raydiffraction analysis of the matrix revealed that it was composed of lowcrystallinity cubic gamma alumina and Y zeolite with a lattice parameterof 2.444 nm, a global SiO₂/Al₂O₃ ratio of 6.7 and a framework SiO₂/Al₂O₃ratio of 14.7.

Catalyst CZ3P was then impregnated with an aqueous solution comprisingammonium biborate. After ageing at room temperature in an atmospheresaturated with water, the impregnated extrudates were dried overnight at120° C. then calcined at 550° C. for 2 hours in dry air. Catalyst CZ3BPwas obtained: NiMoP/alumina-Y doped with boron.

A catalyst CZ3PSi was prepared using the same procedure as for catalystCZ3PB, replacing the boron precursor in the impregnation solution withRhodorsil EP1 (Rhone-Poulenc) silicone emulsion.

Finally, catalyst CZ3PBSi was prepared by impregnating catalyst CZ3Pwith an aqueous solution comprising ammonium biborate and Rhodorsil EP1(Rhone-Poulenc) silicone emulsion. The other steps of the procedure werethe same as those indicated above. The characteristics of catalysts CZ3are summarised in Table 1.

TABLE 1 Characteristics of CZ3 catalysts CZ3 CZ3 CZ3 CZ3 CZ3 CZ3 CZ3Catalyst CZ3 P B Si BSi PB PSi PBSi MoO₃ (wt %) 13.1 12.5 12.8 12.8 12.512.3 12.3 12.1 NiO (wt %) 2.84 2.7 2.8 2.8 2.7 2.7 2.7 2.6 P₂O₅ (wt %) 05.2 0 0 0 5.1 5.1 5.0 B₂O₃ (wt %) 0 0 2.45 0 2.4 2.3 0 2.3 SiO₂ (wt %) 00 0 2.2 2.2 0 2.3 2.2 Al₂O₃ (wt %) 67.5 63.8 65.8 66.0 64.4 62.3 62.360.9 Y (wt %) 16.6 15.7 16.1 16.2 15.8 15.3 15.3 14.9

EXAMPLE 3 Preparation of a Support Containing a Small Amount of NonDealuminated Y Zeolite

Large quantities of a hydrocracking catalyst support containing a smallamount of a globally non dealuminated Y zeolite were produced so as toenable different catalysts based on the same support to be prepared. Tothis end, 8.6% by weight of a non dealuminated Y zeolite with a latticeparameter of 2.453 nm, a global SiO₂/Al₂O₃ ratio of 6.6 and a frameworkSiO₂/Al₂O₃ ratio of 8.6 was used, which was mixed with 91.4% by weightof a matrix composed of ultrafine tabular boehmite or alumina gel soldby Condéa Chemie GmbH under the trade name SB3. This powder mixture wasthen mixed with an aqueous solution containing 66% nitric acid (7% byweight of acid per gram of dry gel) then mixed for 15 minutes. Aftermixing, the paste obtained was passed through a die with cylindricalorifices with a diameter of 1.4 mm. The extrudates were dried overnightat 120° C. then calcined at 550° C. for 2 hours in moist air containing7.5% by volume of water. Cylindrical extrudates 1.2 mm in diameter wereobtained with a specific surface area of 259 m²/g, and a pore volume of0.57 cm³/g and a unimodal pore size distribution centred on 10 nm. An Xray diffraction analysis of the matrix revealed that it was composed oflow crystallinity cubic gamma alumina and Y zeolite with a latticeparameter of 2.444 nm, a global SiO₂/Al₂O₃ ratio of 6.7 with a frameworkSiO₂/Al₂O₃ ratio of 14.1.

EXAMPLE 4 Preparation of Catalysts Containing a Small Amount of NonDealuminated Y Zeolite

Extrudates of the support containing a small amount of non dealuminatedY zeolite with a lattice parameter of 2.444 nm, a global SiO₂/Al₂O₃ratio of 6.7 and a framework SiO₂/Al₂O₃ ratio of 14.1 prepared inExample 3 were dry impregnated with an aqueous solution of a mixture ofammonium heptamolybdate and nickel nitrate, dried overnight at 120° C.in air and finally calcined at 550° C. in air. The oxide weight contentsof catalyst CZ5 obtained are shown in Table 2. The final CZ5 catalystcontained 7.1% by weight of Y zeolite with a lattice parameter of 2.444nm, a global SiO₂/Al₂O₃ ratio of 6.8 and a framework SiO₂/Al₂O₃ ratio of14.9.

Catalyst CZ5 was then impregnated with an aqueous solution comprisingammonium biborate. After ageing at room temperature in an atmospheresaturated with water, the impregnated extrudates were dried overnight at120° C. then calcined at 550° C. for 2 hours in dry air. Catalyst CZ5Bwas obtained. In the same way, catalyst CZ5Si was prepared byimpregnating catalyst CZ5 with a Rhodorsil EP1 (Rhone-Poulenc) siliconeemulsion. The impregnated extrudates were dried overnight at 120° C.then calcined at 550° C. for 2 hours in dry air. Finally, catalystCZ5BSi was prepared by impregnating catalyst CZ5 with an aqueoussolution comprising ammonium biborate and Rhodorsil EP1 (Rhone-Poulenc)silicone emulsion. The impregnated extrudates were dried overnight at120° C. then calcined at 550° C. for 2 hours in dry air.

Extrudates of the support containing the Y zeolite of Example 3 werealso dry impregnated with an aqueous solution of a mixture of ammoniumheptamolybdate, nickel nitrate and orthophosphoric acid, dried overnightat 120° C. in air and finally calcined at 550° C. in air. The oxideweight contents of catalyst CZ5P obtained are shown in Table 2.

Catalyst CZ5P was then impregnated with an aqueous solution comprisingammonium biborate. After ageing at room temperature in an atmospheresaturated with water, the impregnated extrudates were dried overnight at120° C. then calcined at 550° C. for 2 hours in dry air. Catalyst CZ5BPwas obtained: NiMoP/alumina-Y doped with boron.

A catalyst CZ5PSi was prepared using the same procedure as for catalystCZ5PB, replacing the boron precursor in the impregnation solution withRhodorsil EP1 (Rhone-Poulenc) silicone emulsion.

Finally, catalyst CZ5PBSi was prepared by impregnating catalyst CZ5Pwith an aqueous solution comprising ammonium biborate and Rhodorsil EP1(Rhone-Poulenc) silicone emulsion. The other steps of the procedure wasthe same as those indicated above. Fluorine was then added to thiscatalyst by impregnating with a dilute hydrofluoric acid solution so asto deposit about 1% by weight of fluorine. After drying overnight at120° C. and calcining at 550° C. for 2 hours in dry air, catalystCZ5PBSiF was obtained. The characteristics of catalysts CZ5 aresummarised in Table 2.

TABLE 2 Characteristics of CZ5 catalysts CZ5 CZ5 CZ5 CZ5 CZ5 CZ5 CZ5 CZ5Catalyst CZ5 P B Si BSi PB PSi PBSi PBSiF MoO₃ (wt %) 15.2 14.6 14.814.9 14.5 14.3 14.3 14.0 13.7 NiO (wt %) 2.8 2.7 2.7 2.7 2.7 2.7 2.6 2.62.5 P₂O₅ (wt %) 0 4.6 0 0 0 4.5 4.5 4.4 4.35 B₂O₃ (wt %) 0 0 2.3 0 2.32.1 0 2.1 2.1 SiO₂ (wt %) 0 0 0 2.1 2.2 0 2.45 2.3 2.3 F (wt %) 0 0 0 00 0 0 0 1.1 Al₂O₃ (wt %) 74.9 71.4 73.2 73.4 71.5 69.8 69.6 68.1 67.5 Y(wt %) 7.1 6.7 6.9 6.9 6.7 6.6 6.6 6.4 6.4

Catalyst CZ5P was then impregnated with an aqueous solution comprisingmanganese nitrate. After ageing at room temperature in an atmospheresaturated with water, the impregnated extrudates were dried overnight at120° C. then calcined at 550° C. for 2 hours in dry air. Catalyst CZ5PMnwas obtained. This catalyst was then impregnated with an aqueoussolution comprising ammonium biborate and Rhodorsil EP1 (Rhone-Poulenc)silicone emulsion. The impregnated extrudates were then dried overnightat 120C and calcined at 50° C. for 2 hours in dry air to obtain catalystCZ5PMnBSi. Fluorine was then added to this catalyst by impregnating witha dilute hydrofluoric acid solution so as to deposit about 1% by weightof fluorine. After drying overnight at 120° C. and calcining at 550° C.for 2 hours in dry air, catalyst CZ5PMnBSiF was obtained. Thecharacteristics of catalysts CZ5 are summarised in Table 3.

TABLE 3 Characteristics of CZ5 catalysts containing manganese CZ5 CZ5CZ5 Catalyst PMn PMnBSi PMnBSiF MoO₃ (wt %) 14.4 13.8 13.6 NiO (wt %)2.7 2.5 2.5 MnO₂ (wt %) 1.2 1.2 1.15 P₂O₅ (wt %) 4.4 4.2 4.1 B₂O₃ (wt %)0 2.05 2.0 SiO₂ (wt %) 0 2.3 2.3 F (wt %) 0 0 0.85 Al₂O₃ (wt %) 70.767.6 67.0 Y (wt %) 6.6 6.4 6.3

EXAMPLE 5 Preparation of a Support Containing Non Dealuminated Y Zeoliteand a Silica-alumina

We produced a silica-alumina powder by co-precipitating of a compositionof 4% SiO₂, 96% Al₂O₃. A support for a hydrocracking catalyst containingthis silica-alumina and a non globally dealuminated Y zeolite was thenproduced. To this end, 19.5% by weight of a non dealuminated Y zeolitewith a lattice parameter of 2.453 nm, a global SiO₂/Al₂O₃ ratio of 6.6and a framework SiO₂/Al₂O₃ ratio of 8.6 was used, which was mixed with80.5% by weight of a matrix composed of the silica-alumina prepared asabove. This powder mixture was then mixed with an aqueous solutioncontaining 66% nitric acid (7% by weight of acid per gram of dry gel)then mixed for 15 minutes. After mixing, the paste obtained was passedthrough a die with cylindrical orifices with a diameter of 1.4 mm. Theextrudates were dried overnight at 120° C. then calcined at 550° C. for2 hours in moist air containing 7.5% by volume of water. Cylindricalextrudates 1.2 mm in diameter were obtained with a specific surface areaof 365 m²/g, a pore volume of 0.53 cm³/g and a unimodal pore sizedistribution centred on 11 nm. An X ray diffraction analysis of thematrix revealed that it was composed of low crystallinity cubic gammaalumina and Y zeolite with a lattice parameter of 2.444 nm, a globalSiO₂/Al₂O₃ ratio of 6.8 with a framework SiO₂/Al₂O₃ ratio of 14.7.

EXAMPLE 6 Preparation of Catalysts Containing a Non Dealuminated YZeolite and a Silica-alumina

Extrudates of the support containing a non dealuminated Y zeolite with alattice parameter of 2.444 nm, a global SiO₂/Al₂O₃ ratio of 6.8 and aframework SiO₂/Al₂O₃ ratio of 14.7 prepared in Example 5 were dryimpregnated with an aqueous solution of a mixture of ammoniumheptamolybdate and nickel nitrate, dried overnight at 120° C. in air andfinally calcined at 550° C. in air. The oxide weight contents ofcatalyst CZ17 obtained are shown in Table 1. The final CZ17 catalystcontained 16.3% by weight of Y zeolite. X ray diffraction analysis ofthe matrix revealed that it was composed of low crystallinity cubicgamma alumina and Y zeolite with a lattice parameter of 2.444 nm, aglobal SiO₂/Al₂O₃ ratio of 6.6 and a framework SiO₂/Al₂O₃ ratio of 14.2.

Catalyst CZ17 was then impregnated with an aqueous solution comprisingammonium biborate. After ageing at room temperature in an atmospheresaturated with water, the impregnated extrudates were dried overnight at120° C. then calcined at 550° C. for 2 hours in dry air. Catalyst CZ17Bwas obtained.

Extrudates of the support containing the Y zeolite of Example 1 werealso dry impregnated with an aqueous solution of a mixture of ammoniumheptamolybdate, nickel nitrate and orthophosphoric acid, dried overnightat 120° C. in air and finally calcined at 550° C. in air. The oxideweight contents of catalyst CZ17P obtained are shown in Table 4. Thefinal CZ17P catalyst contained 15.4% by weight of Y zeolite. X raydiffraction analysis of the matrix revealed that it was composed of lowcrystallinity cubic gamma alumina and Y zeolite with a lattice parameterof 2.444 nm, a global SiO₂/Al₂O₃ ratio of 6.7 and a framework SiO₂/Al₂O₃ratio of 14.7.

Catalyst CZ17P was then impregnated with an aqueous solution comprisingammonium biborate. After ageing at room temperature in an atmospheresaturated with water, the impregnated extrudates were dried overnight at120° C. then calcined at 550° C. for 2 hours in dry air. Catalyst CZ17BPwas obtained.

The characteristics of catalysts CZ 17 are summarised in Table 4.

TABLE 4 Characteristics of CZ17 catalysts CZ17 CZ17 CZ17 Catalyst CZ17 PB PB MoO₃ (wt %) 13.4 12.7 13.1 12.5 NiO (wt %) 2.9 2.8 2.9 2.7 P₂O₅ (wt%) 0 5.3 0 5.2 B₂O₃ (wt %) 0 0 2.15 2.2 SiO₂ (wt %) 2.68 2.53 2.6 2.5Al₂O₃ (wt %) 64.7 61.2 63.8 59.8 Y (wt %) 16.3 15.4 15.9 15.1

EXAMPLE 7 Comparison of Catalysts for Low Pressure Hydrocracking of aVacuum Gas Oil

The catalysts prepared in the above Examples were employed undermoderate pressure hydrocracking conditions using a petroleum feed withthe following principal characteristics:

Initial point 365° C. 10% point 430° C. 50% point 472° C. 90% point 504°C. End point 539° C. Pour point +39° C. Density (20/4) 0.921 Sulphur(weight %) 2.46  Nitrogen (ppm by weight) 1130

The catalytic test unit comprised two fixed bed reactors in upflow mode.40 ml of catalyst was introduced into each of the reactors. The catalystfor the first hydrotreatment step of the process, HTH548 fromProcatalyse, comprising a group VIB element and a group VIII elementdeposited on alumina, was introduced into the first reactor, throughwhich the feed passed first. A hydrocracking catalyst (CZ5 series) wasintroduced into the second reactor, through which the feed passed last.The two catalysts underwent in-situ sulphurisation before the reaction.It should be noted that any in-situ or ex-situ sulphurisation method issuitable. Once sulphurisation had been carried out, the feed describedabove could be transformed. The total pressure was 8.5 MPa, the hydrogenflow rate was 500 liters of gaseous hydrogen per liter of injected feed,and the hourly space velocity was 0.8 h⁻¹. The two reactors operated atthe same temperature.

The catalytic performances are expressed as the gross conversion at 400°C. (GC), the gross selectivity for middle distillates (150-380° C. cut)(GS) and the hydrodesulphuration (HDS) and hydrodenitrogenation (HDN)conversions. These catalytic performances were measured for the catalystafter a stabilisation period, generally of at least 48 hours, hadpassed.

The gross conversion GC is taken to be:

GC=weight % of 380° C.^(minus) of effluent.

The gross selectivity GS for middle distillates is taken to be:

GS=100*weight of (150° C.-380° C.) fraction/weight of 380° C.^(minus)fraction of effluent.

The hydrodesulphuration conversion HDS is taken to be:

 HDS=(S _(initial) −S _(effluent))/S _(initial)*100=(24600−S_(effluent))/24600*100

The hydrodenitrogenation conversion HDN is taken to be:

HDN=(N _(initial) −N _(effluent))/N _(initial)*100=(1130−N_(effluent))/1130*100

Table 5 shows the gross conversion GC at 400° C., the gross selectivityGS, the hydrodesulphuration conversion HDS and the hydrodenitrogenationconversion HDN for the test catalysts.

TABLE 5 Catalytic activities for catalysts for partial hydrocracking at400° C. GC (wt %) GS (wt %) HDS (%) HDN (%) CZ3 NiMo/Y 50.9 79.8 98.997.1 CZ3P NiMoP/Y 52.2 79.0 99.4 98.4 CZ3B NiMoB/Y 53.3 79.1 99.4 98.4CZ3Si NiMoSi/Y 54.3 79.3 99.4 98.6 CZ3BSi NiMoBSi/Y 54.9 79.5 99.5 98.8CZ3PB NiMoPB/Y 53.5 79.0 99.3 98.5 CZ3PSi NiMoPSi/Y 53.9 79.0 99.25 98.5CZ3PBSi NiMoPBSi/Y 54.8 78.9 99.4 98.9

The results of Table 5 show that the performances of catalyst CZ3 weregreatly improved when B and/or silicon was/were added. The improvementin the gross conversion in particular should be noted, while theselectivity for middle distillates remained constant. Further, thepresence of boron and/or silicon tended to substantially improve the HDSand HDN.

TABLE 6 Catalytic activities for catalysts CZ3 and CZ17 with equivalentcompositions for partial hydrocracking at 400° C. GC GS (wt %) (wt %)HDS (%) HDN (%) CZ17 NiMo/Y-SiAl 53.3 78.9 97.8 97.1 CZ3Si NiMoSi/Y 54.379.3 99.4 98.6 CZ17P NiMoP/Y-SiAl 53.2 79.1 98.25 97.5 CZ3PSi NiMoPSi/Y53.9 79.0 99.25 98.5 CZ17B NiMoB/Y-SiAl 53.7 79.1 98.3 97.1 CZ3BSiNiMoBSi/Y 54.9 79.5 99.5 98.8 CZ17PB NiMoPB/Y-SiAl 53.8 78.7 98.1 97.7CZ3PBSi NiMoPBSi/Y 54.8 78.9 99.4 98.9

The results of Table 6 show that it is advantageous to introduce siliconinto the already prepared catalyst rather than in the form of a supportcontaining silicon obtained from a silica-alumina. This is true whetheror not the catalyst contains phosphorous. It is thus particularlyadvantageous to introduce silicon to a precursor already containinggroup VIB and/or VIII elements and optionally at least one of elementsP, B and F.

Catalysts containing an alumina acidified by boron and/or silicon and aglobally non dealuminated zeolite are thus of particular importance forpartial hydrocracking of a vacuum distillate type feed containingnitrogen at a moderate hydrogen pressure.

EXAMPLE 8 Comparison of Catalysts for Higher Pressure Hydrocracking of aVacuum Gas Oil

The catalysts prepared in Examples 3 and 4 were employed under highpressure (12 MPa) hydrocracking conditions using a petroleum feed withthe following principal characteristics:

Initial point 277° C. 10% point 381° C. 50% point 482° C. 90% point 531°C. End point 545° C. Pour point +39° C. Density (20/4) 0.919 Sulphur(weight %) 2.46  Nitrogen (ppm by weight) 930

The catalytic test unit comprised two fixed bed reactors in upflow mode.40 ml of catalyst was introduced into each of the reactors. Catalyst 1for the first hydrotreatment step of the process, HR360 fromProcatalyse, comprising a group VIB element and a group VIII elementdeposited on alumina, was introduced into the first reactor, throughwhich the feed passed first. The catalyst for the second step, i.e., thehydroconversion catalyst (CZ5 series), was introduced into the secondreactor, through which the feed passed last. The two catalysts underwentin-situ sulphurisation before the reaction. It should be noted that anyin-situ or ex-situ sulphurisation method is suitable. Oncesulphurisation had been carried out, the feed described above could betransformed. The total pressure was 12 MPa, the hydrogen flow rate was1000 liters of gaseous hydrogen per liter of injected feed, and thehourly space velocity was 0.9 h⁻¹.

The catalytic performances are expressed as the temperature at which agross conversion of 70% is produced and by the gross selectivity. Thesecatalytic performances were measured for the catalyst after astabilisation period, generally of at least 48 hours, had passed.

The gross conversion GC is taken to be:

GC=% by weight of 380° C.^(minus) of effluent.

The gross selectivity GS for middle distillates is taken to be:

GS=100* weight of (150° C.-380° C.) fraction/weight of 380° C.^(minus)fraction of effluent.

The reaction temperature was fixed so as to obtain a gross conversion GCof 70% by weight. Table 7 shows the reaction temperature and grossselectivity for catalysts from the CZ5 series.

TABLE 7 Catalytic activities for CZ5 catalysts for hydrocracking T (°C.) GS (%) CZ5 NiMo/Y 396 71 CZ5P NiMoP/Y 395 71.4 CZ5B NiMoB/Y 395 71.5CZ5Si NiMoSi/Y 395 71.5 CZ5BSi NiMoBSi/Y 394 71.8 CZ5PB NiMoPB/Y 39571.2 CZ5PSi NiMoPSi/Y 394 71.5 CZ5PBSi NiMoPBSi/Y 393 71.4 CZ5PBSiFNiMoPBSiF/Y 391 70.9 CZ5PMn NiMoPMn/Y 394 71.2 CZ5PMnBSi NiMoPMnBSi/Y393 71.3 CZ5PMnBSiF NiMoPMnBSiF/Y 390 71.2

Adding boron and/or silicon to the catalyst containing globally nondealuminated zeolite retained the very high selectivity of catalyst CZ5with a lower reaction temperature since a gain of 3° C. in thetemperature was observed with respect to catalyst CZ5PBSi. Further, ifmanganese and/or fluorine was added, an improvement in the convertingactivity was also observed with no degradation of the gross selectivityfor middle distillates.

What is claimed is:
 1. A hydrocracking process comprising contacting ahydrocarbon feed with a catalyst comprising: 0.1-99.7% by weight of atleast one alumina matrix; 0.1-80% by weight of at least one globally nondealuminated Y zeolite with a lattice parameter of more than 2.438 nm, aglobal SiO₂/Al₂O₃ mole ratio of less than 8, and a framework SiO₂/Al₂O₃mole ratio of less than 21 and more than the global SiO₂/Al₂O₃ moleratio; 0.1-30% by weight of at least one group VIII metal and/or 1-40%by weight of at least one group VIB metal (% oxide); 0.1-20% by weightof at least one promoter element selected from the group formed by boronand silicon (% oxide); 0-20% by weight of at least one group VIIAelement; 0-20% by weight of phosphorous (% oxide); 0.1-20% by weight ofat least one group VIIB element; carried out at a pressure of at least 2MPa, a temperature of at least 230° C., using a quantity of hydrogen ofat least 100 Nl hydrogen/l of feed and with an hourly space velocity of0.1-10 h⁻¹.
 2. A process according to claim 1, in which the pressure is2-12 MPa, the temperature is 300-480° C. and the conversion is less than55% by weight.
 3. A process according to claim 2, in which the pressureis 7.5-11 MPa.
 4. A process according to claim 1, in which the pressureis at least 8.5 MPa, the temperature is 300-430° C. and the conversionis at least 55% by weight.
 5. A process according to claim 2, in whichthe feed is hydrotreated prior to hydrocracking.
 6. A process accordingto claim 5, in which the hydrotreatment catalyst contains at least onegroup VIII metal, at least one group VIB metal, phosphorous andoptionally boron.
 7. A process according to claim 2, in which thepressure is 8-11 MPa.
 8. A process according to claim 6, wherein saidcatalyst comprises boron.
 9. A process according to claim 1, whereinsaid catalyst comprises manganese.